Questions tagged [vhf]

Very High Frequency is the frequency range 30-300 MHz.

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2answers
8k views

Looking for a UHF / VHF transceiver for PC.`

I am looking for a simple UHF / VHF transceiver that I can plug into my PC via USB and be able to RX/TX on one channel, using the built in mic... Maybe even record the RX from the freq. Everything I ...
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2answers
1k views

Are chokes necessary for VHF and higher frequencies?

I am trying to install a VHF/UHF antenna on my truck, and I have been studying everything I need to do that. I keep reading about chokes, in particular here: http://www.k0bg.com/choke.html However, ...
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1answer
187 views

What is the best way to get propagation VHF map for FM repeater?

Is there a way to get a professional propagation map for my VHF 50 watt repeater?
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2answers
443 views

2 meter dipole of work vehicle

I am about to purchase a Baofeng HT. I have one I am thinking of using primarily in work truck. I can't really drill holes or have antenna be too obvious. On Amazon I found a 2 meter 70cm 2m dipole....
3
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1answer
148 views

Transverter common versus split-if connections

I have a radio (Flex-1500) that has low level transverter outputs. They can be configured as either a common or split-if. I also have a DEMI transverter that can easily be wired up for common or ...
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1answer
86 views

Heat-shrink as dielectric for bazooka balun?

I'm intending to make a sleeve balun (aka bazooka) for 2m, but rather than keep the lossy coax jacket as a dielectric (I have some RG58), was considering to remove it and replace it with heat shrink ...
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0answers
61 views

How to simulate two antennas in 4nec2

I need to simulate 2 helix antennae placed side by side, and see the resultant radiation pattern. But after adding the second antenna with a separate and when I try to simulate 4nec2, only simulated ...
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2answers
1k views

2m Homebrew Receiver - Chip for frequency [closed]

I am a new HAM trying to design a small, cheap 2m receiver. I've been looking up different circuits and homebrew tutorials, but the closest I seem to find to what I'm looking for seems to always use ...
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4answers
5k views

If i connect two antennas to one radio using a t connector will it work?

If I connect two antennas to one radio using a t connector will it work? If a connect 2 antennas (a mag mount + a dipole?) to the same radio with an adapter will it work normally on 2M band and will ...
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3answers
810 views

VHF 50 Ω Antenna Over 75 Ω TV Coax

I have a 50 Ω VHF airband antenna which I’m planning to install in my loft, for use with a RaspberryPi-based RTLSDR scanner/receiver. I already have a UK-standard UHF/Freeview antenna using standard ...
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2answers
751 views

Is my low-power VHF transmitter dangerous?

I use a Raspberry Pi for transmitting FM on 107.9 Mhz. It uses square waves and has a power of approx 0.085 Watts, but just to be safe: If I have a 1 watt transmitter approximately 1 metre away from ...
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3answers
136 views

Weakly directive VHF/UHF antenna

Most resources around the Internet discuss common antenna types, classifying them between directive (like Yagi) and nondirective (like a simple dipole). Directive antennas are good when you know from ...
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5answers
132 views

Optimal length of HT antenna for VHF UHF and diminishing return

I see folding antennas of various lengths that people are using for for their HT. My question is about the optimal length. I know it may "depend" on many factors so let me know if I need to provide ...
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2answers
406 views

RTL-SDR dongle - what antenna should I use for APRS receive only?

I was following this guide to setup an iGate using an RTL-SDR dongle and a Raspberry Pi. It worked, and I have been able to test it by seeing some APRS packets from a separate transmitter (Arduino+...
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5answers
776 views

What would be the easiest and most cost effective ground system for a startup UHF/VHF station

I just passed both my Technician and General Class license this past weekend, and am now contemplating my first station. To get my feet wet I'm planning on getting a Yaesu FT-7900R Dual band Radio ...
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3answers
300 views

High Altitude Balloon Antenna Design

I'm designing a weather balloon with a club at college. We want to build the antenna from scratch to learn more about antennas but are at a loss as to which antenna design would actually work for high ...
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4answers
170 views

Colorado to Ohio with UV-5R

My brother (in Ohio) just passed his Technician test. We both have UV-5R equivalent radios. I have my General (in Colorado). Without physical modifications to our radios, can we have a QSO? I've been ...
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2answers
2k views

Which Frequency Band(VHF/UHF) is most useful for satellite in MEO?

I want to get to know about the satellite communication at 8000-10000 km, During that, I come across the VHF and UHF. In that I am facing problem for deciding the frequency band for communicating with ...
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3answers
2k views

Feeding a dual-band UHF and VHF Yagi antenna

I just built a UHF Yagi antenna for my HT, and I was thinking about adding VHF elements. If I do, could I just connect the coax directly to both sets of elements without a diplexer?
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1answer
90 views

Help with small dish antenna on 2m/440

I have an oblong dish network antenna that I want to convert to 2m/440 usage. I have seen the one for the 14 foot dish but I do not have one. Not sure if I should wind a coil and mount it in the ...
2
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1answer
719 views

What material is best to design a dipole antenna working at VHF frequency? [duplicate]

I need to design an antenna using the tool FEKO. The antenna is supposed to work in VHF frequency and has a gain of around 2.2 dB. What is the best material to use and what are the specifications of ...
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2answers
389 views

Replace directional antenna by fixed antenna

Given the following specs of a directional antenna: ...
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1answer
77 views

144/430 MHz antenna on 155 MHz?

We have a local radio shop that started selling us Relm P150s with a high gain 9 inch antenna, and those are ok. He also has thrown in longer 15 to 14 inch dual band antennas saying use those in ...
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2answers
703 views

What core material do I need to construct a 1:1 unun for 6M?

I want to build a 1:1 unun for a 6M dipole. Power level 100W. What core material should I use?
2
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1answer
131 views

What were the reasons why ATIS identification was introduced?

I am just about to make my inland waterways’ marine VHF radio license in Germany. In Germany, all inland marine VHF radios must be equipped with an ATIS transmitter, which basically sends the stations’...
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2answers
634 views

Is there a DV VHF calling frequency in the UK?

On the band plan for VHF for the UK, I can see 145.500MHz being the FM calling frequency but I cannot find any for DV. Is there one? In contrast, for UHF, I can see a calling frequency for FM at 433....
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3answers
126 views

Identifying Local Signal

I've been monitoring a signal locally on 159.150mhz (which is allocated for "Civil Defense"). I believe that this frequency is for the local tornado sirens and I would like to be able to decode the ...
2
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2answers
110 views

Filtering VHF FM on my DTV signal

I've noticed that when I transmit on my HT when I'm watching TV (OTA), the signal drops and the screen goes blank (or digital "static") and then returns when I stop. I've replicated the issue by ...
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1answer
234 views

Looking for documentation on Kenwood NX-700 AFO and DEO Signals

I'm studying the accessory connector (DB-25) from a Kenwood NX-700 radio. It seems that I might use the AFO and/or DEO signals, but I haven't been able to get proper documentation on such pins/signals....
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1answer
1k views

Balun and impedance matching suggestions for dipole antenna

I'm a newbie who is attempting to build a half-wave dipole antenna that will be located in the rudder of a sailplane. 123.3 MHz is the most important frequency to me, although it's reasonable to ...
2
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1answer
424 views

VHF antenna / receiver suggestion for a UAV

I am currently working on a student project that involves having a UAV fly an orthogonal path over a series of transmitters -- taking in data (through an arduino-based system for data processing). ...
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0answers
236 views

How can I connect a CW keyer to my Mac and transmit CW on VHF? [duplicate]

I currently have a Kenwood TM-V71A 2m/70cm transceiver that I would like to connect to my Macbook to transmit morse code, using the cocoaModem software. Aside from the cables needed to connect the ...
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2answers
267 views

Using square loop VHF antenna for two different stations/frequency?

I'm using a square loop antenna on the rooftop of approximately 15 square meter area. I use it to communicate with a group of mobile VHF radios using a station room. Right now I'm planning to build ...
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3answers
637 views

Why aren’t emergency services using callsigns?

I’m super new to radio with nobody I know knowing it, so noob alert - plus some extraneous details in case you can comment on any of those. I got a pair of BaoFeng BF-F8HP radios with recommended ...
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3answers
391 views

Weird Harmonic Issue on Raspberry PI FM Transmitter

So I talked to my neighbor about my Raspberry PI, harmonics and his emergency radio. He told me to fire it up, as we saw the FCC sticker on it, meaning it is in compliance with Part 15. I started my ...
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3answers
443 views

High SWR on a Jeep with Spare Tire Mount

I just installed a spare-tire mount and Browning BR-180 dual band antenna on my Jeep JK. Initial SWR testing show nothing higher than 1.4:1 across both bands so I didn't try to tweak it. Then I put ...
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2answers
141 views

What wireless communication technologies can travel long distances with a high bandwidth?

I couldn’t find a better place to ask this question, so I have asked it here. I am looking to transmit and receive internet connectivity wirelessly over a distance of 6 miles (9.7 km) with a minimum ...
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5answers
1k views

Can I contact the International Space Station using my Baofeng UV5R?

I saw this article but I can't imagine the power output, (eight watts max) would be enough to be picked up by the ISS at 200 miles above me. Similarly, I don't know if the preamp on the receiver ...
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1answer
181 views

Colinear Vhf antenna

Textbook colinear vertical antenna designs show coax cable with alternating braid to centre configuration. Commercial whips seem to utilise a single wire as the radiating element with .66 velocity ...
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1answer
85 views

Handheld multiband radio for a ham firefighter?

I live half a mile from my volunteer fire station. We are toned out on a VHF frequency by a neighboring municipality, and we provide mutual aid for their fire department that is toned out on an 800-...
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1answer
103 views

Power handling of a simple VHF ground plane

The ARRL welcome pamphlet contains instructions on building a simple ground plane antenna and specifically comments on its use by handy-talkies. However, I wonder what the actual capability of this ...
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1answer
650 views

What is pinout for headphone FM radio antenna?

My Android phone (as many others) have FM radio receiver on-board. But apparently, it has no internal VHF antenna at all, since there is no signal at all w/o headphones plugged in and sound quality ...
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2answers
150 views

V/U Packet Rate Limits

I'm studying for the General exam and I've encountered some questions about maximum baud rates on various bands. They seem... extremely optimistic. Given the trouble I've had investigating 9600 baud ...
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1answer
72 views

Are there any satellite email reflectors?

I'm just getting started using amateur satellites and would like to subscribe to an email reflector, but I can't find one. Is there anything out there?
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1answer
87 views

Mobile VHF/UHF antenna coupling to surrounding objects?

Will a mobile antenna --either mag mount or NMO mount-- couple to surrounding objects such as tall trees, taller trucks, buses, or even people walking by? If that is the case, would you get slightly ...
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1answer
487 views

2m loop with sense antenna for DF

I would like to construct a 2m Loop with a sense antenna. I have built just a loop antenna with great success that is resonant at 2m finding null's works quite well on local repeater outputs. I would ...
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1answer
64 views

VTS messages vs AIS

When arriving in a port, complementary to her AIS signal (encoded VHF message) it seems that the vessel also has to emit a voice message on a predifined VHF frequency to identify herself as part of ...
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2answers
542 views

Airband VHF antenna challenge

I have a very difficult antenna design/installation challenge. I need to install an VHF antenna (118 to 140 MHz) into a nearly all carbon fiber glider. The radio provides 5 watts and 50 ohm, and most ...
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1answer
85 views

how does this collinear antenna work?

I was looking for a cheap and easy to build 2M/70cm vertical. I found this: http://vk2zoi.com/articles/dual-band-high-gain-flower-pot/ Here are the plans to build it: But I don't really understand ...
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1answer
153 views

Radio Modem suggestion [closed]

I need to transmit digital data, from an Arduino, Raspberry or alike, but using VHF band (aprox 150 MHz), would anyone care to suggest a cost effective device to use as transceiver? 10W would be ...